An economic evaluation of invasive alien plant control programmes in the mountain catchment areas of the Western Cape Province, South Africa

Abstract:

The study area for this thesis is situated in the centre of one of the worlds major centres of biological diversity. The mountain catchment areas were surveyed during 1994/95 to determine the extent of invasive alien plants in this highly sensitive fire prone environment with poor soils on steep slopes and high rainfall. These catchments deliver 60% of the water of the Western Cape but only cover 9% of the land surface. Earlier studies in the field of hydrology have concluded that afforestation with the same genera as the ones that are posing the biggest invasion threat to these catchments reduce streamflow from the catchments where they were planted. As a result of this hydrological research a value could be placed on streamflow from the catchments. The primary aim of this study was to quantify the costs and benefits of the clearing of invasions dominated by Pinus, Hakea and Acacia species. To determine the costs and benefits, resource and management data was analysed, enabling me to estimate the effects of management actions. These analyses produced results on both the contribution of natural variables and the effects of management efficiency and productivity on the viability of clearing programmes. The management models produced results that confirmed the notion that the cheapest option of conserving streamflow from Fynbos catchments is to keep them clear of invasives. The results did however also highlight some very interesting questions concerning approaches to invasive alien plant clearing. Some of these results showed the risks involved in using only one ecosystem service benefit stream, as representative of all ecosystem services. Using only runoff as a basis for calculating project worth turned out to be risky at times. These results lead to the analysis of some hypothetical case studies on water quality and catchment resilience, which can be used as a starting point for future research in the field of resource economics. Although the original aim of the project was not to evaluate management activities in terms of its value towards biodiversity, the contribution of diversity towards catchment worth and resilience showed up a number of times. These should be researched more in the future. The quality of regional scale environmental data also turned out to be an issue highlighted by the study. Very little high quality hydrological data needed for strategic planning for the catchments are available. These shortcomings need to be addressed for important strategic planning for the Fynbos catchments. The study went further and evaluated the short-term socio-economic benefits in terms of the macroeconomics of the Western Cape Province. These also produced some extremely interesting results indicating that the Fynbos Working for Water Projects succeed in its goal of reconstruction and development. Employment and redistribution of wealth turned out to be two of the major socio-economic benefits of the projects.